TY - JOUR
T1 - Complex structure of a proto-brown dwarf
AU - Riaz, B.
AU - Machida, M. N.
N1 - Funding Information:
The Joint ALMAObservatory is operated by ESO,AUI/NRAO, andNAOJ.BR acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG) Projekt number RI 2919/2–1. This research used the computational resources of the HPCI system provided by (Cyber Sciencecenter, Tohoku University; Cybermedia Center, Osaka University, Earth Simulator, JAMSTEC) through the HPCI System Research Project (Project ID:hp180001,hp190035). This study was supported by JSPS KAKENHI Grant Numbers JP17K05387, JP17H02869, JP17H06360, and 17KK0096 (MNM). Simulations reported in this paper were also performed by 2018 and 2019 Koubo Kadai on Earth Simulator (NEC SX-ACE) at JAMSTEC
Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2021/7/1
Y1 - 2021/7/1
N2 - We present ALMA 12CO (2-1), 13CO (2-1), C18O (2-1) molecular line observations of a very young proto-brown dwarf system, ISO-OPH 200. We have conducted physical+chemical modelling of the complex internal structure for this system using the core collapse simulations for brown dwarf formation. The model at an age of ∼6000 yr can provide a good fit to the observed kinematics, spectra, and reproduce the complex structures seen in the moment maps. Results from modelling indicate that 12CO emission is tracing an extended (∼1000au) molecular outflow and a bright shock knot, 13CO is tracing the outer (∼1000 au) envelope/pseudo-disc, and C18O is tracing the inner (∼500 au) pseudo-disc. The source size of ∼8.6 au measured in the 873-μm image is comparable to the inner Keplerian disc size predicted by the model. A 3D model structure of ISO-OPH 200 suggests that this system is viewed partially through a wide outflow cavity resulting in a direct view of the outflow and a partial view of the envelope/pseudo-disc. We have argued that ISO-OPH 200 has been mis-classified as a Class Flat object due to the unusual orientation. The various signatures of this system, notably, the young ∼616-yr outflow dynamical age and high outflow rate (∼1 × 10-7 M⊙ yr-1), silicate absorption in the 10-$\rm{\mu m}$ mid-infrared spectrum, pristine ISM-like dust in the envelope/disc, comparable sizes of the extended envelope and outflow, indicate that ISO-OPH 200 is an early Class 0 stage system formed in a star-like mechanism via gravitational collapse of a very low mass core.
AB - We present ALMA 12CO (2-1), 13CO (2-1), C18O (2-1) molecular line observations of a very young proto-brown dwarf system, ISO-OPH 200. We have conducted physical+chemical modelling of the complex internal structure for this system using the core collapse simulations for brown dwarf formation. The model at an age of ∼6000 yr can provide a good fit to the observed kinematics, spectra, and reproduce the complex structures seen in the moment maps. Results from modelling indicate that 12CO emission is tracing an extended (∼1000au) molecular outflow and a bright shock knot, 13CO is tracing the outer (∼1000 au) envelope/pseudo-disc, and C18O is tracing the inner (∼500 au) pseudo-disc. The source size of ∼8.6 au measured in the 873-μm image is comparable to the inner Keplerian disc size predicted by the model. A 3D model structure of ISO-OPH 200 suggests that this system is viewed partially through a wide outflow cavity resulting in a direct view of the outflow and a partial view of the envelope/pseudo-disc. We have argued that ISO-OPH 200 has been mis-classified as a Class Flat object due to the unusual orientation. The various signatures of this system, notably, the young ∼616-yr outflow dynamical age and high outflow rate (∼1 × 10-7 M⊙ yr-1), silicate absorption in the 10-$\rm{\mu m}$ mid-infrared spectrum, pristine ISM-like dust in the envelope/disc, comparable sizes of the extended envelope and outflow, indicate that ISO-OPH 200 is an early Class 0 stage system formed in a star-like mechanism via gravitational collapse of a very low mass core.
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U2 - 10.1093/mnras/stab547
DO - 10.1093/mnras/stab547
M3 - Article
AN - SCOPUS:85108661649
VL - 504
SP - 6049
EP - 6066
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -